#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>

size_t my_strcspn(const char* str, const char* group)
{
	size_t ret = 0;
	while (strchr(group, *str) == NULL)
	{
		str++;
		ret++;
	}
	return ret;
}

int main()
{
	char str[] = "abcs11222";
	char group[] = "s112";
	size_t len = my_strcspn(str, group);
	printf("len = %u\n", len);
	return 0;
}